Forming hollow ribs in metal sheet

ABSTRACT

Apparatus for forming generally triangular hollow ribs in a metal sheet including first roller die means having complementary roll surfaces defining an opening provided with a base forming section, a generally flat sheet receiving section disposed in a plane parallel to the base section and a pair of diverging sidewalls extending from opposite sides of the base section to the sheet section. Second roller die forming means having complementary roll surfaces defining an opening having a generally flat base forming section, a generally flat sheet receiving section disposed in a plane parallel to the base section and a pair of diverging sidewall sections having an included angle of less than the first die means diverging sidewall sections but greater than zero. Third roller die means having a pair of work surfaces adapted to engage the outer surfaces of the upper portions of the sidewalls of the sheet and urge the same transversely inwardly to establish a gap between the upper surfaces which is less than the transverse width of the base. Non-rotating fourth die means disposed generally transversely inwardly with respect to the third roller die means and adapted to be in supporting contact with the lower inner surfaces of the rib sidewalls and the rib base as the sheet passes through the third roller die means. A sheet forming die for supporting the interior of a generally triangular hollow rib during formation thereof having a pair of sheet engaging feet. Each sheet engaging foot having a lower surface for engaging the inner surface of the rib base and a side surface for engaging the inner lower surface of one rib sidewall. The base and sidewall engaging surface of each foot at an angle of less than 90*. A method of forming generally triangular hollow ribs in a metal sheet. Forming the sheet by horizontally disposed roller die means to establish a generally flat rib base sector disposed in a plane generally parallel to the plane of the sheet. Simultaneously forming a pair of angularly directed rib sidewalls disposed on opposite sides of the rib base sector and connecting the base sector with the remainder of the sheet. The sidewalls diverging outwardly from the base to the sheet. Subsequently, progressively roller die forming the sheet without materially altering the width of the base sector or the sidewalls by reducing the included angle between the sidewalls and increasing the distance between the plane of the sheet and plane of the rib base sector. Subsequently transversely reducing the distance between the upper portions of the sidewalls until the distance between them is less than the width of the base, while providing supporting die means in contact with the interior surface of the base sector and the interior surface of the lower portions of the sidewalls.

United States Patent King et al.

[ 51 3,707,088 51 Dec.26,1972

541 FORMING HOLLOW RIBS 1N METAL SHEET [72] Inventors-Richard E. King, Pittsburgh; Richard C. Pfaff, Murrysville, both [21] Appl. No.: 139,404

52 U.S.Cl; ....'..72/l78,72/l80,72/181 51 men. .mms/os 5s FieldofSearch ..72/l8l,178,180,176

[5 6] References Cited UNITED STATES PATENTS 1,505,207 8/1924 Kux et al. ..72/l76 R18,760 3/1933 Yoder .....72/l80 1,140,087 5/1915 Vannaman ..72/18l X 1,574,397 2/1926 Kirsch ..72/181 2,012,796 8/1935 Kurtze ..72/l8l X 2,027,215 1/1936 Williams ..72/181 1,942,466 1/1934 Adams, .lr... ..72/l81 X 2,251,967 8/1941 Yoder ..72/l81 X Primary Examiner-Milton S. Mehr AttorneyArnold B. Silverman [57] ABSTRACT flat sheet receiving section disposed in a plane parallel to the base sectjonand a pair of diverging sidewall sections having an includ'dangiear less than the' first die means diverging sidewall sections but greater than zero. Third roller die means having a pair of work surfaces adapted to engage the outer surfaces of the upper portions of the sidewalls of the sheet and urge the same transversely'inwardly to establish a gap between the upper surfaces which is less than the transverse width of the base. Non-rotating fourth die means disposed generally transversely inwardly with respect to the third roller die means and adapted to be in supporting contact with the lower inner surfaces of the rib sidewalls and the rib base as the sheet passes through the third roller die means.

A sheet forming die forsupporting the interior of a generally triangular hollow rib during formation thereof having a pair of sheet engaging feet. Each sheet engaging foot having a lower surface for engaging the inner surface of the rib base and a side surface for engaging the inner lower surface of one rib sidewall. The base and sidewall engaging surface of each foot at an angle of less than 90.

A method of forming generally triangular hollow ribs in a metal sheet. Forming the sheet by horizontally disposed roller die means to establish a generally flat rib base sector disposed in a plane generally parallel to the plane of the sheet. Simultaneously forming a pair of angularly directed rib sidewalls disposed on opposite sides of the rib base sector and connecting the base sector with the remainder of the sheet. The

- sidewalls diverging outwardly from the base to the sheet. Subsequently, progressively roller die forming 18 Claims, 25 Drawing Figures PATENTED nu: 2 6 m2 SHEET 1 OF 5 FIG. 2.

- I l-c INVENTORS.

a F 6 mm H M m C M 0 BA mm HH CC I RR PA'TENTEDHEB 1912 I 3. 707,088

SHEET 2 OF 5 FIG. 3.

FIG. 4.

FIG. 6.

//0 [/4 88 FIG. 7.

98 //6 I00 INVENTORS.

RICHARD C. PFAFF 8 RICHARD E. KING Maw A Horney PATENTEDneczs I972 SHEET 5 BF 5 FIG. /2.

I74 I78 44 I82 I76 FIG. 16.

l/VVENTORS.

RICHARD C. PFAFF a R/CHARD E. KING a s); 3 W

A Horney FORMING HOLLOW RIBS IN METAL SHEET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus and method for establishing generally triangular, hollow ribs in a sheet element such that the ribs have a restricted throat opening adjacent the plane of the sheet and a base portionof enlarged dimension with respect to the throat opening. More specifically, this invention relates to ap paratus and method for establishing such ribs sequentially through a number of die forming operations in order to effect uniform rib profile formation.

2. Description of the Prior Art Various means of forming integral hollow rib structures in a sheet adapted for uses such as in the building field have been known. It has also been known to provide a building product sheet wherein the sheet has a plurality of longitudinal generally parallel triangular ribs having a broader base than the apex gap disposed adjacent the plane of the sheet. See US Pat. Nos. 1,574,586, 1,828,842 and 1,975,842. These patents show such a profiled sheet employed in building construction uses such as roof construction, floor deck and wall construction wherein a keyed interlock with poured concrete is desired. One of the principal problems encountered with such structures has been the inability to provide apparatus and a method which effectively and consistently will produce the desired rib profile, while maintaining the sharp angular intersection between the rib base and the upwardly converging rib sidewalls.

ln general, in forming such a ribbed sheet it has been customary to use sequential roller die forming operations. As a result of the restricted throat entrance to the triangular rib, however, such forming has been accomplished in general solely by the use of exterior tooling. For example, it has been known to employ roller dies on the rib sidewall as well as rib base exterior surfaces to attempt to effect a sharp angular intersection between the base and sidewalls. One inadequacy of such a system has been the lack of ability to control the angle of intersection. In addition, such forming has tended to create an undesirable upwardly convex bow in the rib base which should be substantially flat.

A further complication has been the need to attempt to establish such a ribbed sheet profile while remaining within the rather tight competitive economic confines encountered in building products of this type. It is es-' sential that the amount of product rejected is kept to an absolute minimum. Also, it is important that the product emerge from the roll forming operations at a sufficiently high lineal rate to justify the expense of both labor and capital investment in the equipment.

SUMMARY OF THE INVENTION The method and apparatus of this invention have solved the above-described problems by providing a method and apparatus which permit substantially complete elimination of product rejects based upon departures from desired rib profile tolerances. This is accomplished in a positive fashion which assures uniformity of profile and adapts for variation in sheet properties such as gage, alloy and temper, which variations frequently occurwithin metal tolerances acceptable to sheet fabricators.

The apparatus for forming the'triangular hollow ribs of this invention has a first roller die means which have complementary roll surfaces. The complementary roll surfaces define an opening provided with a rib base forming section, a generally flat sheet receiving section disposed in a plane parallel to the rib base forming section and a pair of sidewalls connecting the base section with the sheet receiving section and diverging from the former to the latter. Second roller die means have complementary surfaces defining a base forming section, a

sheet receiving section and a pair of diverging sidewalls having an included angle less than the first die means diverging sidewalls, but greater than zero. Third roller die meanshave a pair of work surfaces adapted to engage the outer surfaces of the upper portions of the sheet sidewalls and urge the same transversely inwardly to establish a gap between the upper sidewall portions which is less than the width of the rib base. Non-rotating fourth die means are positioned generally transversely inwardly of the third die means and are adapted to be in supporting contact with the lower inner surfaces of the sidewalls and the rib base as the sheet passes through the third die means. This fourth die means has a pair of die feet adapted to provide the desired interior surface supporting contact. Also, the fourth diemeans may be provided with a die section having a generally triangular configuration corresponding to that of the rib profile.

The method of this invention provides a means of forming one or more generally triangular shaped hollow ribs in a metal sheet through a sequential forming operation. The generally flat metal sheet is subjected to an initial forming operation by horizontally disposed roller die means which establish a generally flat rib base sector having the width of the final rib base and a pair of angularly directed divergingrib sidewalls which extend upwardly to the plane of the sheet and also have the same width as the final rib sidewalls. The initial rib structure is then subjected to additional progressive roller die forming which reduces the included angle between the sidewalls while maintaining the width and flatness of the base and sidewalls. This portion of the forming is preferably terminated when the included angle between the sidewalls is less than about 25. The distance between'the upper portions of the sidewalls is subsequently reduced by deforming each sidewall transversely inwardly until the distance between the sidewalls is less than the width of the base. This last forming stage is accomplished while providing die means in supporting contact with the interior surface of the base and interior surface of the lower sidewall portions.

It is an object of this invention to provide a method and apparatus for effectively providing a uniform,

generally triangularly shaped hollow rib in a metalsheet through a sequential forming operation which may be economically performed at a rapid rate with a low percentage of product rejects on the basis of rib profile. 7

It is another object of this invention to provide such a method and apparatus wherein conventional roller forming technology may be employed to the point of having a generally rectangular rib profile and subsequently unique means are provided to establish the desired rib profile having a restricted throat opening without distorting the flatness and width of the rib base section and sidewalls.

It is another object of this invention to. provide a method and apparatusfor forming such ribs in such a fashion that a reasonable range of variations in gage, temper and alloy of the metal sheet will not have a meaningful influence on the dimension or profile configuration of the generally triangular ribs.

It is yet another object of this invention to provide such a method and apparatus wherein one or more additional ribs may be partially or entirely formed simultaneously with the formation of the initial rib during the same pass of the sheet through the dies.

These and other objects of the-invention will be more fully understood from the following description of the invention, on reference to the illustrations appended hereto. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken away perspective view of a composite floor structure employing a form of ribbed sheet made in accordance with this invention.

FIG. 2 is a profile of a form of triangularly ribbed sheet made in accordance with this invention.

FIGS. 3 through 11 illustrate a preferred form of a roller die contour employed in sequential forming of the triangularly ribbed sheet structure of this invention. FIGS. 3a through 1 la illustrate sheet segment profiles corresponding to the stages of fabrication illustrated in FIGS. 3 through 1 l.

FIG. 12 illustrates a form of fixed internal die employed in this invention.

FIG. 13 illustrates a side elevational view of a portion of the die shown in FIG. 12.

FIG. 14 illustrates a modified form of non-rotating die employed in this invention. FIG. 15 illustrates a front elevational view of another type of non-rotating die employed in this invention.

.FIG. 16 is a side elevational view of the die structure shown in FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detail to FIG. 1, it is seen that there is shown a metal sheet 2 having a number of generally triangular hollow ribs 4. Each rib has a base wall 6 and a pair of sidewalls 8, 10 which connect the transverse marginal sides of base wall 6 with sheet 2. The sidewalls 8, l converge from the base 6 to the sheet 2 and define a restricted throat entrance 14 to the hollow rib 4. As is shown'in FIG. 1, concrete 16 may be poured onto the rib deck and as a result of the configuration of the ribs 4 the concrete will set and provide a keyed interlock which resists relative separating movement between the concrete l6 and the sheet 2. Also shown are a plurality of metal reinforcing rods 18.

Referring now to FIG. 2, it is seen that the sheet profile is such, in the form shown, as to provide three whole ribs 4, a right fractional rib 20 and a left fractional rib 22. In joining adjacent panels the fractional rib 20 of one panel or sheet 2 is secured to the fractional rib'22 of the adjacent panel or sheet. It is noted that the base wall 6 of the rib has a transverse width a and the sidewalls 8, have a width b. The restricted or throat opening 14 has a width 0 which is smaller than the width 0. It will be appreciated that as a result of the relative proportions of base wall 6 and throat entrance 14 conventional roller die forming techniques em- JIM) ployed in forming open, rectangular hollow ribs cannot be employed as a result of the physical obstruction to inserting and removing a roller die into the rib interior.

Referring now to FIGS. 3 through 1 1, a preferred die structure arrangement and process of this invention will be considered. While in order to facilitate simplicity of illustration the figures have shown only the complementary working surfaces of the dies and not the power, transmission and joumaling structures, it willbe appreciated that these are of the conventional type employed with roller die forming operations. Each roller die will be suitably joumaled and connected to a driving motorby means of suitable interposed transmission elements including a clutch and gear boxfThe precise size motor and transmission means will be selected in accordance with the objectives with respect to roller die load and desired angular velocity by conventional means.

As used herein, the terms horizontal,vertical, upper, lower and words of similar import shall be employed solely for convenience and simplicity of reference'and shall be used solely for illustrative purposes and are not limiting of the orientation employed in this invention. Also, for convenience of illustration, the rolls will be shown without regard to whether the work surface of a given roll is defined by varying the contour of a single roll or composed of a plurality of roll sectors-assembled to define an identical work surface.

Referring now to FIG. 3 and corresponding FIG. 3a, it is seen that this station of the roller dies'has an upper roller die 26 and a complementary lower roller die 28. The work surfaces 30, 32 of roller dies 26, 28, respectively, define an elongated sheet receiving opening 34. It is noted that opening 34 will be positioned at the transverse location of the sheet where the initial rib is to be formed. This will generally be at the transverse center of the sheet. At the transverse outer portions of these rollers, there are two annular gaps 38, 40 which permit ready passage of the sheet therethrough with reduced frictional contact. In the form shown, the rolls will be considered as being disposed horizontally, i.e. rotating about a horizontal axis, and the sheet will be considered as being fed in either web form or from a coil in a horizontal direction sequentially through the successive roller die stands.

Referring to FIG. 3a which shows the profile of the sheet as it emerges from the roller dies shown in FIG. 3, it is seen that the originally generally flat sheet 42 has had a center portion reformed by providing a rib base sector 44 and a pair of rib sidewalls 46, 48. The rib base 44 is preferably substantially flat and of the same transverse width as the final rib base wall. It is disposed in a plane generally parallel to the plane of the remainder of I IOGOIZ Ol 16 Referring now to FIG. 4, there is shown the second roller die stand which has cooperating roller dies 50, 52 defining a sheet receiving opening 54 and gaps 56, 58.

Referring to FIGS. 4 and 4a it is seen that the rib base 44 has been moved farther downwardly to increase the space between the plane of the base 44 and the plane of the remainder of the sheet 42. In addition, the included angle B defined between sidewalls 46, 48 has been reduced with respect to the angle A. It is also noted that the transverse portions 60, 62 remain substantially flat through this stage of forming.

Referring now to FIGS. 5 and 5a, it is seen that there is shown a pair of roller dies 64, 66 which'cooperate to define sheet receiving opening 68' and clearance regions or gaps 70, 72. The angle C included between sidewalls 46, 48 reflects a further reduction in the included angle and is smaller than angle B. It will be appreciated .that base 44 and sidewalls 46, 48 have retained their original width and substantially flat configuration. Thus, the first three stages of roller die forming have resulted in the initial formation of the rib base 44 and sidewalls 46, 48 with subsequent stages providing a deepening of the rib structure without alterin g the dimensions of its base or wall portions.

As the sheet continues to move horizontally through the roller die structures it will next reach the forming stage shown in FIGS. 6 and 6a. The roller dies 74, 76 cooperate to define sheet receiving opening 78 and have gaps 80, 82 disposed at their transverse. outer extremities. It will be noted that the rib base wall 44 has been moved farther away from the plane of flat sheet 42 and additional relative closing movement between sidewalls 46, 48 has produced an included angle D which is smaller than angle C.

Should it be desired to form solely a single rib within the sheet, the remaining roller die stands may be provided with gaps or clearances such as 80, 82 in order to reduce the amount of friction between the sheet and roller dies. lt will generally, however, be desired to form additional ribs at positions spaced transversely with respect to the initial rib. This may be accomplished most efficiently by initiating the sequential forming of one or more ribs, be they of the same dimensions as the initial rib or different, while forming of the initial rib is still in process. Such additional ribs may be begun simultaneously with the initial rib or subsequent thereto, but preferably prior to completion of the initial rib. This serves to reduce substantially the total number of die stands required for multiple rib formation. Such a structure will be shown and considered in connection with the remaining stages of formation of the initial rib. For simplicity of description it will be understood that the rib shape and roller die mating surfaces (only a portion of which will be illustrated) will be identical with those employed in forming the initial rib and that completion of the additional ribs will be effected in the same manner as completion of the initial rib, but such completion will be accomplished at stages downstream with respect to the direction of the movement of the sheet.

As is shown in FIGS. 7 and 7a, roller dies 84, 86 cooperate to provide a sheet receiving opening 88 of substantially increased width with respect to the prior sheet receiving openings shown in FIGS. 3 through 6. Considering first the continued formation of the initial rib, it is noted that the included angle E between sidewalls-46, 48 represents a further reduction effected through relative transverse closing movement of sidewalls 46, 48 and the angle E is smaller than angle D. Also, the rib base wall 44 has been moved farther away from the plane of sheet 42. It will be noted that, as was previously true, disposed transversely adjacent the upper extremities of sidewalls 46, 48 are flat sheet sections 90, 92, respectively. In addition, the transverse outer portions of the sheet 42 have been subjected to the initial forming stages to establish a second rib base 94 and a second rib sidewall 96. (Only one half of the second and third ribs have been illustrated, but it will be appreciated that the other half will be a mirror image of the half shown.) This has been accomplished by cooperation of surfaces 98, of roller dies 84, 86. In similar fashion second rib sidewall 96 has been formed by cooperation of die surfaces 102, 104. In similar fashion third rib base and sidewall sections 106, 108 are formed by cooperation of die surfaces 110, 112, 114, 116. It is noted that this form results in the second and third ribs being formed simultaneously. If desired, the, second and third ribs may be formed sequentially.

i The initial stage of forming of the initial rib is completed in the fashion shown in FIGS. 8 and 8a in order to establish a generally rectangularly configurated hollow rib structure. As is shown in these drawings roller dies 120, 122 cooperate to define sheet receiving opening 124. As is shown in FIG. 8a the angle F established between sidewalls 46, 48 is smaller than angle E. At this point the sidewalls 46, 48 preferably are approaching a perpendicular relationship with 1 respect to the base wall 44. It is generally preferred that the included angle F between sidewalls 46, 48 be less than 25, but greater than zero. This facilitates withdrawal of die section 126 from the hollow rib and eliminates undesired binding. The sheet sections 90, 92 immediately adjacent the ribs remain substantially the same, while the second rib base 94 and third rib base 106 and sidewalls 96, 108 have assumed the configuration shown in FIG. 4 with respect to the initial rib.

It is apparent that at this point the limit of practical roller die formation of the hollow rib has been reached. In order to provide for effective formation of the triangular rib, alternate means must be employed to complete fabrication.

Reference is now made to FIGS. 9 and 9a. In addition to roller dies 128 and 130, which have working surfaces indicated generally by the reference numerals 132, 134, 136 and 138, operating to continue the formation of the second and third ribs, other dies are employed to complete the formation of the initial rib. It is seen that a pair of roller dies 140, 142, which are vertical dies rotating about a vertically oriented axis, are provided. It is also noted that these roller dies have an annular tapered working surface 146, 148, respectively. The roller dies 140, 142 cooperate to define a downwardly diverging rib forming surface. Each roller die 140, 142 has its maximum diameter at the upper extremity of its working surfaces 146, 148 and its minimum diameter at the lower portion of its working surface 146, 148. As is shown in FIG. 9a, rib base portion 44 has been moved farther away from the plane of sheet 42, but retains its initial flat configuration and transverse width. The sidewalls 46, 48 now diverge downwardly from the sheet 42 to the base 44 and define an included, angle M. Theworking surfaces 146,

. 148 of dies 140, 142 are engaged with the exterior surface of the upper extremity 150, 152 of sidewalls 46, 48, respectively, and urge the same transversely inwardly. In addition, the dies 140, 142 have upper die surfaces 156, 158 which cooperate with roller die 128 to maintain the flatness of sheet sectors 90, 92.

' Referring now to theintersection of sides 46, 48 with base 44 it will be appreciated that there is a need to maintain the critical angular relationship between these rib wall elements. Die 130 has a generally channel shaped work surface 160 which isin surface to surface contact with the outer surface of the base 44. and the exterior surface of lower portions 164, 166, respectively,of sidewalls 46, 48. In addition, a pair of non-rotating die feet 170, 172 have portions in surface to surface contact with the inner surface 'of base wall 44 and the inner'surface of lower portions 164, 166 of the inner surface of sidewalls 46, 48 in order to resist undesired inward deformation and distortion of the intersection between sidewalls 46, 48 and base 44. In this fashion the vertical dies 140, 142 urge the upper portion 150, 152 of the sidewalls 46, 48 transversely inwardly to establish an angle M which provides a gap g'between the upper extremities 150, 152. Gap g is smaller than thetransverse width of base 44.

Depending upon the relationship between the gap g and the width of base 44 which is desired, one may terminate thestationary die and roller die forming operation at any stage after the gap g becomes smaller than the width of base 44. It is preferable for many uses to have the width of base 44 about I to 4 times the width of gap g. This providesfor effective integral structural reinforcement and appropriate I interlock where concrete or other poured material is to'be used in connectionwith the formed sheet. In those instances where the pattern is provided for aesthetic considerations in addition to the functional stiffening, the proportions may be varied to meet the desired aesthetic objectives.

The stationary die structure shown in FIG. 9 will now be considered in greater detail with reference to FIGS. 12 and 13. As is shown in FIG. 12, a sheet 42 is provided with a rib having sidewalls 46, 48 and base wall 44. For clarity of illustration roller dies 128, 130, 140, 142 have not been shown. It will be appreciated that each die foot 170, 172 has a cross sectional configuration which is generally rectangular, but is provided with a'tapered extension 174, 176, respectively. Foot 170 has a first surface 178 in surface to surface contact with the inner surface of base 44 closely adjacent to the intersection of base 44 with sidewall 46. In addition, foot result of the support provided by die feet 170, 172

against the operation of the working surfaces of dies It will be appreciated that the die feet 170, 172 are preferably anchored in stationary position and are disposed generally transversely inwardly with respect to roller dies 140, 142 although feet 170, 172 may be slightly longitudinally displaced with respect to the position of roller dies 140, 142. In this fashion the longitudinal movement of the sheet will establish relative movement with respect'to feet 170, 172 in order to facilitate forming of the desired rib profile.

One convenient means of providing such a die foot structure is shown in FIG. 13. As is there shown the die foot 170 has an elongated body portion 186' which terrninates in a pilot surface 188 which facilitates ing of the die feet in such fashion as to provide a cantilevered support for the end 192 which contains pilot surface 188. I v I Reference is now made to FIGS. 12, 15 and 16. It is seen that shown schematically is an anchor plate 196 which has means for effecting vertical adjustment. A depending die supporting element 198 is secured to the anchor plate 196 by means of fasteners received. in openings 200 200 shown schematically. The die supporting element 198 has a restricted web portion 202 which terminates at its lower extremity in a pair of recesses 204 which receive feet 170, 172 whichare inclined transversely inwardly and upwardly; Die supporting element 198 is shown in detail in FIGS. '15 and 16. Fasteners passing through openings in walls defining recesses204 secure the feet 170, 172 in position.

An alternate form of foot die structure is shown in FIG. 14 wherein the two feet are formed integrally with die supporting element 206. Each foot has a base engaging surface 208, 210 and sidewall engaging surface 212, 214. lnterposed between surfaces 208 and 210 is a concavely configurated recess wall portion 216 which serves to minimize the amount of frictional contact .between the lower die surface and the rib base. In the preferred form, the sidewall engaging surfaces 212, 214 will contact the interior surface of the rib sidewalls 46, 48 over about 5 to 60 percent of the surface.

Reference is now made to FIGS. 10 and 10a wherein it is shown that a next stage has roller dies 218, 220. Roller dies 218, 220 are horizontally disposed and roller dies 226, 228 which have work surfaces 230, 232 cooperate to define a larger included angle than roller dies 140, 142 and result in angle N being the included angle between side surfaces 46, 48. In addition, a channel shaped working surface 236 is provided in die 220 and cooperate with die feet 170, 172 to provide the desired profile for the hollow rib. Referring now to FIG. 10a, it is seen that the gap g is smaller than the gap 3 and that the rib structure is more pronounced than in FIG. 9a.

FIGS. 1 l and 11a show the final forming stage for the initial rib. Roller die 240 cooperates with roller die 242 to define sheet receiving opening 244. A modified form of stationary die 246 is provided. This die has a generally triangular cross sectional configuration and preferably is of solid section. Stationary die 246 has a 106012 ons generally identical peripheral contour as the hollow rib profile, but of slightly reduced dimension to permit the die to be received within the interior of the hollow rib. It has base surface 248 which is adapted to be in surface to surface contact with the interior of base 44. in addition, it has sidewall surfaces 250, 252 which are adapted to be in surface to surface contact with portions of sidewalls 46, 48, respectively. It is noted that the final form of profile of the initial rib shown in FIG. 1 1a has a gap g", which is substantially smaller than the transverse width of base 44. It is further noted that the base wall 44 and sidewalls 46, 48 have retained their substantially flat configuration and transverse width throughout the forming process. Finally, it should be noted that sequentially from FIGS. 7a to 11a, the progressive simultaneous forming of second and third ribs has continued.

EXAMPLE ln order to illustrate the sort of panel which may be produced by the method andapparatus of this invention a galvanized steel sheet having a gage of was progressively provided with three complete ribs and two partial ribs. The ribs had substantially flat base portions and sidewalls. The overall width of the ribbed sheet was 24 inches with the ribs being spaced apart 6 inches on centers. The rib base measured 1% inches, the rib sidewalls measured 2 inches and the gap between the upper portions of the sidewalls measured one-half inch. This structure possessed uniformity of rib profile throughout its longitudinal extent and sheet flatness.

It should be noted that the process and apparatus of this invention are adapted to be used with a wide range of materials including a wide range of metals such as steel and aluminum. Steel, which may be decoratively and/or protectively finished, is preferably employed in the range of 16 to 24 gage.

It will, therefore, be appreciated that this invention provides a method of forming generally triangular hollow ribs in a metal sheet wherein the initial forming step involves forming of the sheet by means of horizontally disposed roller die means to establish a generally flat rib base sector disposed in a plane generally parallel to the plane of the sheet and a pair of angularly directed rib sidewalls disposed on opposite sides of the rib base sector. The sidewalls diverge outwardly from the rib base to the remainder of the sheet. In the preferred form of method, the initial roll die means establishes the final width and sheet contour of both the rib base sector and the sidewalls. The method involves subsequently progressively roller die forming the sheet to reduce the included angle between the sidewalls while maintaining the width and flatness of the rib base sector and sidewalls. Subsequently the transverse distance between the'upper portions of the rib sidewall is reduced by decreasing the included angles between sidewalls. until the gap or distance between the upper portions is less than the width of the rib base sector. This gap reducing step is accomplished while supporting the interior surface of the rib base and the interior surface of lower portions of the sidewalls. The forming stage involving the final gap reduction after the initial forming by use of roller die means is preferably initiated et rib sidewalls have an included J0; angle of about but greater than zero. Preferably, roller dies rotating about a vertical axis are employed reduce the sidewall gap while interior support is provided as described above.

Another advantageous feature of this invention is the initiation of forming of one or more additional ribs, displaced transversely with respect to the initial rib, either simultaneously with formation of the initial rib or during the intermediate stages of initial rib formation.

lt-will, therefore, be appreciated that the method and apparatus of this invention provides for effective production of one or more integral hollow ribs in a metal sheet wherein the hollow rib has a restricted throat opening. In addition, it provides for forming a generally triangularly shaped hollow rib wherein the throat entrance may have a substantially reduced width as compared with the transverse width of the rib base. This is accomplished mechanically by the means of die members which are adapted to provide internal reinforcing support at certain critical intersecting locations within the hollow rib structure as the sheet is moved sequentially longitudinally through the apparatus. The interior die may preferably consist of more than one die sector with a final sector having a substantially solid generally triangular transverse cross sectional configuration.

All of this is accomplished at economic, desirable commercial roller die fabricating speeds and without the need for a substantial investment in additional equipment. The rib profile may be reproduced sequentially or partially simultaneously at other transverse locations on the sheet in order to provide a sheet having a plurality of complete and/or partial ribs.

It will be appreciated that while specific reference has been made herein to sheets adapted to be used as building products such as panels, roof elements anddeck, numerous other uses of the resulting product will be readily apparent to those skilled in the art.

Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details may be made without departing from the invention as defined in the appended claims.

We claim:

1. Apparatus for forming generally triangular hollow ribs in a metal sheet, comprising first roller die means having complementary roll surfaces defining an opening provided with a rib base forming section, a generally flat sheet receiving section disposed in a plane parallel to said base section and a pair of diverging sidewall sections extending from opposite transverse sides of said base section to said sheet receiving section,

second roller die means having complementary roll surfaces defining a second opening having a second rib base forming section, a generally flat second sheet receiving section disposed in a plane parallel to said second base section and a pair of second diverging sidewall sections having an included angle of less than said first die means diverging sidewall sections but greater than zero and said second sidewall sections extending from opposite sides of said second base section said second sheet section,

4. The sheet forming apparatus of claim 3 including third roller die-means having a pair of opposed work surfaces adapted to engage the upper portions of the sidewalls. and urge the same transversely inwardly to establish a gap between 1 the upper sidewall surfaces which is less than the transverse width of rib base section, and V non-rotating fourth die means disposed generally transversely inwardly with respect to the adjacent third roller die means and adapted to be in supporting contact with the lower inner surfaces of said rib sidewalls and said rib base section said sheet is subjected to relative longitudinal movement through said third die means. 2. The sheet forming apparatus of claim 1 including said first and second roller die means define generally horizontally aligned openings for the sequential passage of sheet therethrough, said first and second roller die means rotate about generally horizontally disposed axes, said third roller die means rotate about generally vertically disposed axes, and said work surfaces of said fourth die means disposed at a lower level than saidwork surfaces of said third die means.- i 3. The sheet forming apparatus of claim 2 including said fourth die means has pair of die feet with each said die foot positioned to engage the inner surfaces of said sheet rib base andone said rib sidewall, and each said die foot has a lower surface disposed generally parallel to said sheet rib base and an inclined transversely inwardly directed side surface intersecting therewith.

said fourth die means has a generally triangular die portion having a substantially solid transverse cross section and disposed downstream from said side die feet with respect to the direction of sheet travel, and

said generally triangular die portion having an outer surface provided with a generally flat base portion and a pair of upwardly transversely converging sidewall surfaces. V

5. The sheet forming apparatus of claim 4 including said third roller die means having bevelled work surface which have a maximum diameter at the uppermost portion and a minimum diameter at the lowermost portion thereof, whereby said third roller die means work surfaces urge said rib sidewalls transversely inwardly as said sheet moves longitudinally therethrough.

6. The sheet forming apparatus of claim 5 including said fourth die means die feet each having a generally rectangular cross sectional configuration with an elongated tapered lower transverse outer portion,

said die feet disposed in a downwardly and transver sely outward position, and

said die feet secured in generally aligned relationship with respect to said generally triangular die and at a position upstream with respect to the direction of sheet travel therefrom.

7. The sheet forming apparatus of claim 5 including said first and second roller die means each has at least two pairs of roller dies for sequentially reforming said sheet, and

at least one additional series of said first, second, third and fourth die means disposed in a position spaced transversely from said first series, whereby at least one additional said generally triangular rib may be formed within said sheet at positions spaced transversely from the initial rib either simultaneously, sequentially orpartially formed simultaneously with respect to the formation of said initial rib.

8. A sheet forming die for supporting the interior of a generally triangular hollow rib during formation thereof, comprising a pair of sheet engaging feetwith each foot having a lower working surface for engaging the inner surface of the rib base and a side working surface for engaging the inner lower surface of one rib sidewall,

said rib base and sidewall engaging surfaces of each said foot intersecting at an included angle of less than means securing said feet in relatively fixed position with respect to each other, 7

said die having a second die component having a generally solid transverse cross section and an outer generally triangular peripheral configuration, and

means securing said sheet engaging feet in aligned position with respect to said triangular die portion with said sheet engaging surfaces of said feet in generally aligned positions with respect to portions of the outer peripheral surface of said triangular die. The forming die of claim 8 including said sheet engaging feet are of substantially identical transverse width with respect to said corresponding portions of said triangular die portion, and

said triangular die portion having an exterior surface which hasa substantially identical configuration as said hollow rib but of slightly reduced size to permit the former to be received within the latter.

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said sheet engaging feet are of substantially identical transverse width with respect to said corresponding portions of said triangular die portion, and

said triangular die portion having an exterior surface which has a substantially identical configuration said hollow rib but of slightly reduced sizeto permit the former to be received within the latter. 7

10. A method of forming generally triangular hollow ribs in a metal sheet, comprising providing a general horizontally disposed flat metal sheet,

forming said sheet by means of horizontally disposed roller die means to establish a generally flat rib base sector disposed in a plane generally parallel to the plane of said sheet and a pair of angularly directed rib sidewalls disposed on opposite sidesof said rib base sector connecting said base with the remainder of said sheet and diverging outwardly from said rib base to said sheet,

progressively roller die forming said sheet to reduce the included angle between said sidewalls while maintaining the width and flatness of said rib base sector and moving said base away from said sheet, and

reducing the transverse distance between the upper IUMHZ (H2O portions of said rib sidewalls until the distance is less than the width of said base while providing die means in contact with portions of the interior surface of said rib base and the interior surface of the lower portions of said sidewalls.

l 1. The forming method of claim including said progressive roller die forming of said rib sidewalls to reduce the included angle between said sidewalls is effected by horizontally disposed roller dies and terminating said forming when said rib sidewalls have an included angle of less than about and subsequently reducing said transverse distance between the upper portions of said rib sidewalls by means of vertical roller dies which contact the exterior surface of said sidewalls and supporting said interior surfaces of said rib base and said lower sidewall portions by non-rotating die means.

12. The forming method of claim 1 1 including providing said vertical roller dies with a larger diameter at their upper extremity than at their lower extremity,

effecting contact between a pair of elongated shoe elements of said fixed die means on the interior of said base surface and said sidewall surfaces'solely at and adjacent the intersection of said base and sidewalls, and

effecting contact between said exterior rib sidewall surfaces and said vertical rollers at a position spaced closer to the plane of said sheet than said shoe elements contact with said interior surfaces of said rib base and sidewalls.

13. The forming method of claim 12 including restraining the remainder of said sheet adjacent said rib against vertical displacement during said transverse reduction of the distance between said sidewall upper portions and generally simultaneously therewith supporting the interior of said generally triangular hollow rib by means of a nonrotating interiorly disposed die.

14. The forming method of claim 13 including after at least partial formation of the initial rib forming additional ribs at positions spaced transversely from said initial rib by means of the same sequence of operations as employed with respect to said initial rib.

15. The forming method of claim 13 including moving said' sheet longitudinally between said roller die stations and said fixed die stations and effecting longitudinal insertion of said elongated shoe elements into said ribs, and

longitudinally separating said rib from said elongated shoe elements after 1 the forming operation performed by said shoe elements and cooperating dies has been completed.

16. The forming method of claim 15 including establishing said final base width and sidewall width at single roller die station, and

establishing the final base and sidewall shape but not relative orientation of said sidewalls and base at said single die station.

17. The forming method of claim 16 including subsequent to the initial forming step but prior use of said vertical roller dies subjecting said sidewalls to relative closing movement sequentially at at least four die stations, and

transversely closing said gap between said upper sidewall portions by sequentially moving said sheet through at least two forming stations.

18. The forming method of claim 16 including initiating formation of two additional ribs spaced transversely outwardly from said first rib simultaneously with the initiation of transverse closing movement of sa1d sidewall gap while contacting said initial rib interior surfaces with said fixed die means. 

1. Apparatus for forming generally triangular hollow ribs in a metal sheet, comprising first roller die means having complementary roll surfaces defining an opening provided with a rib base forming section, a generally flat sheet receiving section disposed in a plane parallel to said base section and a pair of diverging sidewall sections extending from opposite transverse sides of said base section to said sheet receiving section, second roller die means having complementary roll surfaces defining a second opening having a second rib base forming section, a generally flat second sheet receiving section disposed in a plane parallel to said second base section and a pair of second diverging sidewall sections having an included angle of less than said first die means diverging sidewall sections but greater than zero and said second sidewall sections extending from opposite sides of said second base section said second sheet section, third roller die means having a pair of opposed work surfaces adapted to engage the upper portions of the sidewalls and urge the same transversely inwardly to establish a gap between the upper sidewall surfaces which is less than the transverse width of rib base section, and non-rotating fourth die means disposed generally transversely inwardly with respect to the adjacent third roller die means and adapted to be in supporting contact with the lower inner surfaces of said rib sidewalls and said rib base section said sheet is subjected to relative longitudinal movement through said third die means.
 2. The sheet forming apparatus of claim 1 including said first and second roller die means define generally horizontally aligned openings for the sequential passage of sheet therethrough, said first and second roller die means rotate about generally horizontally disposed axes, said third roller die means rotate about generally vertically disposed axes, and said work surfaces of said fourth die means disposed at a lower level than said work surfaces of said third die means.
 3. The sheet forming apparatus of claim 2 including said fourth die means has pair of die feet with each said die foot positioned to engage the inner surfaces of said sheet rib base and one said rib sidewall, and each said die foot has a lower surface disposed generally parallel to said sheet rib base and an inclined transversely inwardly directed side surface intersecting therewith.
 4. The sheet forming apparatus of claim 3 including said fourth die means has a generally triangular die portion having a substantially solid transverse cross section and disposed downstream from said side die feet with respect to the direction of sheet travel, and said generally triangular die portion having an outer surface provided with a generally flat base portion and a pair of upwardly transversely converging sidewall surfaces.
 5. The sheet forming apparatus of claim 4 including said third roller die means having bevelled work surface which have a maximum diameter at the uppermost portion and a minimum diameter at the lowermost portion thereof, whereby said third roller die means work surfaces urge said rib sidewalls transversely inwardly as said sheet moves longitudinally therethrough.
 6. The sheet forming apparaTus of claim 5 including said fourth die means die feet each having a generally rectangular cross sectional configuration with an elongated tapered lower transverse outer portion, said die feet disposed in a downwardly and transversely outward position, and said die feet secured in generally aligned relationship with respect to said generally triangular die and at a position upstream with respect to the direction of sheet travel therefrom.
 7. The sheet forming apparatus of claim 5 including said first and second roller die means each has at least two pairs of roller dies for sequentially reforming said sheet, and at least one additional series of said first, second, third and fourth die means disposed in a position spaced transversely from said first series, whereby at least one additional said generally triangular rib may be formed within said sheet at positions spaced transversely from the initial rib either simultaneously, sequentially or partially formed simultaneously with respect to the formation of said initial rib.
 8. A sheet forming die for supporting the interior of a generally triangular hollow rib during formation thereof, comprising a pair of sheet engaging feet with each foot having a lower working surface for engaging the inner surface of the rib base and a side working surface for engaging the inner lower surface of one rib sidewall, said rib base and sidewall engaging surfaces of each said foot intersecting at an included angle of less than 90*, means securing said feet in relatively fixed position with respect to each other, said die having a second die component having a generally solid transverse cross section and an outer generally triangular peripheral configuration, and means securing said sheet engaging feet in aligned position with respect to said triangular die portion with said sheet engaging surfaces of said feet in generally aligned positions with respect to portions of the outer peripheral surface of said triangular die. The forming die of claim 8 including said sheet engaging feet are of substantially identical transverse width with respect to said corresponding portions of said triangular die portion, and said triangular die portion having an exterior surface which has a substantially identical configuration as said hollow rib but of slightly reduced size to permit the former to be received within the latter.
 10. A method of forming generally triangular hollow ribs in a metal sheet, comprising providing a general horizontally disposed flat metal sheet, forming said sheet by means of horizontally disposed roller die means to establish a generally flat rib base sector disposed in a plane generally parallel to the plane of said sheet and a pair of angularly directed rib sidewalls disposed on opposite sides of said rib base sector connecting said base with the remainder of said sheet and diverging outwardly from said rib base to said sheet, progressively roller die forming said sheet to reduce the included angle between said sidewalls while maintaining the width and flatness of said rib base sector and moving said base away from said sheet, and reducing the transverse distance between the upper portions of said rib sidewalls until the distance is less than the width of said base while providing die means in contact with portions of the interior surface of said rib base and the interior surface of the lower portions of said sidewalls.
 11. The forming method of claim 10 including said progressive roller die forming of said rib sidewalls to reduce the included angle between said sidewalls is effected by horizontally disposed roller dies and terminating said forming when said rib sidewalls have an included angle of less than about 25*, and subsequently reducing said transverse distance between the upper portions of said rib sidewalls by means of vertical roller dies which contact the exterior surface of said sidewalls and suPporting said interior surfaces of said rib base and said lower sidewall portions by non-rotating die means.
 12. The forming method of claim 11 including providing said vertical roller dies with a larger diameter at their upper extremity than at their lower extremity, effecting contact between a pair of elongated shoe elements of said fixed die means on the interior of said base surface and said sidewall surfaces solely at and adjacent the intersection of said base and sidewalls, and effecting contact between said exterior rib sidewall surfaces and said vertical rollers at a position spaced closer to the plane of said sheet than said shoe elements contact with said interior surfaces of said rib base and sidewalls.
 13. The forming method of claim 12 including restraining the remainder of said sheet adjacent said rib against vertical displacement during said transverse reduction of the distance between said sidewall upper portions and generally simultaneously therewith supporting the interior of said generally triangular hollow rib by means of a non-rotating interiorly disposed die.
 14. The forming method of claim 13 including after at least partial formation of the initial rib forming additional ribs at positions spaced transversely from said initial rib by means of the same sequence of operations as employed with respect to said initial rib.
 15. The forming method of claim 13 including moving said sheet longitudinally between said roller die stations and said fixed die stations and effecting longitudinal insertion of said elongated shoe elements into said ribs, and longitudinally separating said rib from said elongated shoe elements after the forming operation performed by said shoe elements and cooperating dies has been completed.
 16. The forming method of claim 15 including establishing said final base width and sidewall width at single roller die station, and establishing the final base and sidewall shape but not relative orientation of said sidewalls and base at said single die station.
 17. The forming method of claim 16 including subsequent to the initial forming step but prior use of said vertical roller dies subjecting said sidewalls to relative closing movement sequentially at at least four die stations, and transversely closing said gap between said upper sidewall portions by sequentially moving said sheet through at least two forming stations.
 18. The forming method of claim 16 including initiating formation of two additional ribs spaced transversely outwardly from said first rib simultaneously with the initiation of transverse closing movement of said sidewall gap while contacting said initial rib interior surfaces with said fixed die means. 